Some vehicles, such as pick-up trucks and some semi-trailers, have a rear cargo bed which is open at its top. These cargo beds are surrounded by a frame, typically including spaced-apart, generally parallel sidewalls, a front wall and a rear wall or tailgate.
There are many situations in which it is desirable to cover the open cargo bed to protect its contents from the weather or to prevent materials from being accidently dislodged from the bed. Furthermore, covering an open cargo bed is mandatory in those states which have enacted laws requiring a cover over any materials hauled in a truck or trailer.
Many securing arrangements for covers presently in use have one or more serious disadvantages. For example, with one type of cover, spaced-apart snaps along the outside of the sidewalls of the vehicle bed cooperate with mating snaps attached to a flexible cover. In another well-known type of cover, the cover is provided with grommets along its outer edge which are secured to hooks on the outer surfaces of the sidewalls of the bed. These types of covers have the disadvantages that tension forces on the covers are not distributed evenly along the edge of the cover but are concentrated in the smaller areas defined by the grommets or snaps. The material used for these covers sometimes is not strong enough to withstand such concentrated loads.
The need for strong covering material also prevents the use of relatively thin inexpensive woven or non-woven materials in the manufacture of such prior art covers. As a further disadvantage, these covers are typically dimensioned to stretch tightly in a horizontal manner across the top of the cargo bed directly between the cargo bed sidewalls, which unduly limits the amount of materials that can be hauled at any one time.
Securing devices which keep the cover in place by securing the entire length of a marginal edge portion typically depend on friction between the securing device and the cover material. However, the tensile forces on the cover are occasionally great enough due to wind forces when the vehicle is moving to cause the cover to come loose from such prior art securing devices. Thus, although these devices have the advantage that light weight material can be used for the cover, an improved device for holding such covers in place is needed.